A case of primary liver carcinoma with intracavitary cardiac extension is presented. A 36-year-old female was admitted to our surgical clinic with dyspnea and generalized edema. Echocardiography and superior vena cavography demonstrated a large filling defect in the right atrium. After a diagnosis of acute cardiac failure due to an intracardiac tumor, the patient was operated upon immediately. A right atriotomy exposed a large yellow mass within the right atrium, which was not adherent to the atrial wall. The mass was in continuity with similar material in the inferior vena cava and right hepatic vein. With a suspicion of hepatic malignancy, the atrial tumor was removed, and debulking of the mass in the inferior vena cava and right hepatic vein was performed. A postoperative histological examination of the tumor showed hepatocellular carcinoma. Her postoperative course was uneventful, and she was discharged from the hospital. Intracardiac extension of hepatoma is rarely encountered. In this clinical setting, long-term survival cannot be anticipated from any surgery, but palliative clearing of the atrium and inferior vena cava may be of value in preventing cardiac arrest causing sudden death.